Penicillins and cephalosporins are β-lactam antibiotics which are most widely and frequently used in the clinic. However, the acquisition of resistance to β-lactam antibiotics by various pathogens severely has had a damaging effect on maintaining the effective treatment of bacterial infections. The most significant known mechanism related to the acquisition of bacterial resistance is the production of class A, C, and D β-lactamases having a serine residue at the active center. These enzymes decompose the β-lactam antibiotic, resulting in the loss of the antimicrobial activities. Class A β-lactamases preferentially hydrolyze penicillins while class C β-lactamases have a substrate profile favoring cephalosporins. As commercially available β-lactamase inhibitors, clavulanic acid, sulbactam, and tazobactam are known, and these inhibitors are effective mainly against class A β-lactamase producing bacteria, and used as a mixture with a penicillin antibiotic. However, 250 types or more of β-lactamases have been reported to date, and among them, in addition to the expansion of class C β-lactamases as well as extended-spectrum β-lactamase (ESBL) belonging to class A and D β-lactamases, further resistant bacteria which produce class A KPC-2 β-lactamase decomposing even carbapenem as a last resort for β-lactam antibiotic is being considered as a problem. The development of a novel inhibitor is strongly demanded as the commercially available inhibitors are ineffective against these β-lactamases.
Also, in recent years, infectious diseases caused by the above-mentioned resistant bacteria as pathogenic bacteria are found not only in severe infectious disease but also occasionally in community-acquired infectious disease, so that the development of a novel inhibitor which can be used in combination with the drug of first alternative (for example, penicillins or cephalosporins) in a city is strongly demanded. However, although there are a report of potential inhibitors and a report for treating severe infectious disease, there are only a few candidates under development.
In recent years, U.S. Pat. No. 7,112,592 (Patent document 1), U.S. Pat. No. 7,612,087 (Patent document 2) and WO 2009/091856 (Patent document 3) have disclosed that certain kinds of diazabicyclooctane derivatives are promising compounds in the treatment of infectious diseases as an antibiotic having non-β-lactam structure or a β-lactamase inhibitor. As a process for preparing the same, in addition to the above-mentioned documents, the process disclosed in WO 2010/126820 A2 (Patent document 4) has been known.